The present invention concerns an auditory ossicle prosthesis comprising a plate with a groove on its upper surface and a shaft eccentrically applied to the underside, of the general type disclose in German Patent Application No. P 30 36 245.9-35 (corresponding to U.S. application Ser. No. 385,371, filed May 26, 1982), now U.S. Pat. No. 4,473,909 and a process for its manufacture.
Prostheses of the aforementioned type are used for the complete or partial reconstruction of the auditory ossicle tract located in the tympanum. In particular, excellent acousto-mechanical coupling may be obtained between the sound receiving tympanum and--in the absence of a functioning malleus and/or incus--the sound conducting stapes stirrup and the stapes footplate by means of the local-anatomically optimum fitting of the implant.
The decisive condition for such favorable oto-surgical results is the use of bioactive prosthesis material, in particular bioglass ceramics or bioglass.
It is known that bioactive bone replacement materials of this type have a certain surface solubility, which presumably represents a precondition necessary for the achievement of the bond between the bone and the implant. On the other hand, this particular property under especially unfavorable local anatomical conditions, such as those present when the implantation of a prosthesis takes place in soft tissue or if the prosthesis is in contact with soft tissue, may lead to a deterioration of the long term stability of the implant.